I'm seeing much better, and more consistent, altitude recording with the 945 than I ever got from F3, FR645, F5+.
My F3 was useless, the 645 and F5+ were usable but often would have a 30'-50' difference at the end of runs that started and ended at the same point.
This Sunday should be a good test. I'm doing a HM that starts and ends at the same place and has ~350' of drop in the first 5 miles by just trending down and makes it all back up in 2 hills in the last 5k.